/*
 *  Copyright 2005 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.mybatis.generator.api;

import java.io.File;

import org.mybatis.generator.exception.ShellException;

/**
 * This interface defines methods that a shell should support to enable the
 * generator to work. A "shell" is defined as the execution environment (i.e. an
 * Eclipse plugin, and Ant task, a NetBeans plugin, etc.)
 * 
 * The default ShellCallback that is very low function and does not support the
 * merging of Java files. The default shell callback is appropriate for use in
 * well controlled environments where no changes made to generated Java files.
 * 
 * @author Jeff Butler
 */
public interface ShellCallback {
	/**
	 * This method is called to ask the shell to resolve a project/package
	 * combination into a directory on the file system. This method is called
	 * repeatedly (once for each generated file), so it would be wise for an
	 * implementing class to cache results.
	 * 
	 * The returned <code>java.io.File</code> object:
	 * <ul>
	 * <li>Must be a directory</li>
	 * <li>Must exist</li>
	 * </ul>
	 * 
	 * The default shell callback interprets both values as directories and
	 * simply concatenates the two values to generate the default directory.
	 * 
	 * @param targetProject
	 * @param targetPackage
	 * @return the directory (must exist)
	 * @throws ShellException
	 *             if the project/package cannot be resolved into a directory on
	 *             the file system. In this case, the generator will not save
	 *             the file it is currently working on. The generator will add
	 *             the exception message to the list of warnings automatically.
	 */
	File getDirectory(String targetProject, String targetPackage) throws ShellException;

	/**
	 * This method is called if a newly generated Java file would overwrite an
	 * existing file. This method should return the merged source (formatted).
	 * The generator will write the merged source as-is to the file system.
	 * 
	 * A merge typically follows these steps:
	 * <ol>
	 * <li>Delete any methods/fields in the existing file that have the
	 * specified JavaDoc tag</li>
	 * <li>Add any new super interfaces from the new file into the existing file
	 * </li>
	 * <li>Make sure that the existing file's super class matches the new file</li>
	 * <li>Make sure that the existing file is of the same type as the existing
	 * file (either interface or class)</li>
	 * <li>Add any new imports from the new file into the existing file</li>
	 * <li>Add all methods and fields from the new file into the existing file</li>
	 * <li>Format the resulting source string</li>
	 * </ol>
	 * 
	 * This method is called only if you return <code>true</code> from
	 * <code>isMergeSupported()</code>.
	 * 
	 * @param newFileSource
	 *            the source of the newly generated Java file
	 * @param existingFileFullPath
	 *            the fully qualified path name of the existing Java file
	 * @param javadocTags
	 *            the JavaDoc tags that denotes which methods and fields in the
	 *            old file to delete (if the Java element has any of these tags,
	 *            the element is eligible for merge)
	 * @return the merged source, properly formatted. The source will be saved
	 *         exactly as returned from this method.
	 * @throws ShellException
	 *             if the file cannot be merged for some reason. If this
	 *             exception is thrown, nothing will be saved and the existing
	 *             file will remain undisturbed. The generator will add the
	 *             exception message to the list of warnings automatically.
	 */
	String mergeJavaFile(String newFileSource, String existingFileFullPath, String[] javadocTags) throws ShellException;

	/**
	 * After all files are saved to the file system, this method is called once
	 * for each unique project that was affected by the generation run. This
	 * method is useful if your IDE needs to be informed that file system
	 * objects have been created or updated. If you are running outside of an
	 * IDE, your implementation need not do anything in this method.
	 * 
	 * @param project
	 *            the project to be refreshed
	 */
	void refreshProject(String project);

	/**
	 * Return true if the callback supports Java merging, otherwise false. The
	 * <code>mergeJavaFile()</code> method will be called only if this method
	 * returns <code>true</code>.
	 * 
	 * @return a boolean specifying whether Java merge is supported or not
	 */
	boolean isMergeSupported();

	/**
	 * Return true if the generator should overwrite an existing file if one
	 * exists. This method will be called only if
	 * <code>isMergeSupported()</code> returns <code>false</code> and a file
	 * exists that would be overwritten by a generated file. If you return
	 * <code>true</code>, then we will log a warning specifying what file was
	 * overwritten.
	 * 
	 * @return true if you want to overwrite existing files
	 */
	boolean isOverwriteEnabled();
}
